A programme to monitor volcanic activity about the active summit crater of Mt Erebus was conducted by the NZ Geological Survey
from December 1980 to December 1985. The surveys were made annually in conjunction with the International Mount Erebus Seismic
Studies project.
The main components of the survey were as follows:
(1) Horizontal deformation of the summit area was monitored by a triangulation network of five stations on the rim of Main
Crater connected to two stations on more stable ground on the outer rim. (Five further stations were added in 1984 to include
Side Crater and the Nausea Knob area.)
(2) Vertical deformation was monitored by four tilt levelling (i.e. dry tilt) patterns.
(3) Horizontal and vertical deformation of Main Crater floor was monitored by an eight-marker alignment before it was destroyed
by eruptions in 1984.
(4) Short term horizontal deformation during declining eruptive activity in December1984 was monitored by repeat electronic
distance measurements (EDM) of four lines on the outer slopes of Main Crater.
(5) An alignment of seven stations near, and including, the original Erebus Hut, was surveyed annually to determine whether
Camp Flow was a lava flow or a lava bomb-covered active glacier. (It proved to be the latter, moving downslope at 20-30 mm
per year.)
The most significant volcanic deformation was a relatively minor 50 mm expansion across the 500 m wide Main Crater, most of
which occurred during increased seismicity in 1982 and during a period of eruptions in 1984. No significant tilt exceeding
20 microradians was recorded and only localised movements attributed to geothermal effects were detected on the crater floor.
No short term changes were observed during the declining eruptions in late 1984. The expansion of Main Crater was interpreted
as minor inflation across a rift system extending southwest from Main Crater through Side Crater associated with the increased
gas and heat flux. There was no evidence for a substantial volume change in magma stored at shallow levels or a blockage in
the the conduit beneath the lava lake.

A single publications contains all the information on the surveys and includes the 12 New Zealand references giving more specific
information on the survey methods and results and the actual location of the survey stations:
Otway, P.M. Blick, G.H. Scott, B.J. Volcanic deformation monitoring on Mount Erebus: methods and results of geodetic surveys,
1980-1985. In: Volcanological and environmental studies of Mount Erebus, Antarctica. Kyle P.R. (ed) Washington: American
Geophysical Union. 1994. pp.57-68 [Antarctic research series: 66] ISBN 0875908756
The actual field observations were recorded in a series of field books, and the computations are on computer printouts and
manual calculations, all held by IGNS Science, Wairakei, New Zealand. Please contact Brad Scott B.Scott@gns.cri.nz